Production of single-walled carbon nanotubes by a hydrogen arc discharge method

Abstract

A method for producing a single-walled carbon nanotube product by a hydrogen arc discharge method includes providing an anode including graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen; providing a cathode in the atmosphere; and inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product. Additionally, the single-walled carbon nanotube product may be soaked in an acid or an oxidative reactant and heated under vacuum to produce a hydrogen storage material.

What is claimed is:  
     
       1. A method for producing a single-walled carbon nanotube product comprising: 
       providing an anode at least a portion of which includes graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen;  
       providing a cathode in the atmosphere;  
       inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product, wherein the growth promoter is selected from the group consisting of sulfur and a solid sulfide;  
       soaking the single-walled carbon nanotube product in an acid or an oxidative reactant; and  
       heating the soaked single-walled carbon nanotube product under vacuum to produce a hydrogen storage material.  
     
     
       2. The method according to  claim 1 , wherein the cathode is a movable graphite rod. 
     
     
       3. The method according to  claim 1 , wherein the anode includes a cylinder pressed from a mixture of evenly dispersed graphite powder, catalyst metal, and growth promoter. 
     
     
       4. The method according to  claim 1 , wherein the anode includes a graphite cylinder with at least one hole defined in its top surface, wherein the hole includes evenly dispersed graphite powder, catalyst metal, and growth promoter. 
     
     
       5. The method according to  claim 1 , wherein the anode is a cylinder pressed from the graphite powder, the catalyst metal, and the growth promoter under a pressure of 10 MPa. 
     
     
       6. The method according to  claim 1 , wherein the anode is rotatable. 
     
     
       7. The method according to  claim 1 , wherein the atmosphere is selected from the group consisting of pure hydrogen and a mixture of at least 80% hydrogen and 20% argon by volume. 
     
     
       8. The method according to  claim 1 , wherein the catalyst metal includes at least two metals selected from the group consisting of Fe, Co, Ni, and Y. 
     
     
       9. The method according to  claim 1 , wherein the catalyst metal is present in the anode in an amount of 2.5 to 5 atom percent. 
     
     
       10. A method for producing a single-walled carbon nanotube product comprising: 
       providing an anode at least a portion of which includes graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen;  
       providing a cathode in the atmosphere; and  
       inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product, wherein the growth promoter is selected from the group consisting of sulfur and a solid sulfide;  
       wherein the cathode and a top surface of the anode are arranged at an angle with respect to one another of from 30° to 80°.  
     
     
       11. A method for producing a single-walled carbon nanotube product comprising: 
       providing an anode at least a portion of which includes graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen;  
       providing a cathode in the atmosphere; and  
       inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product,  
       wherein the growth promoter is selected from the group consisting of sulfur and a solid sulfide;  
       wherein the anode has a first diameter, the cathode has a second diameter smaller than the first diameter, and wherein a ratio of the first diameter to the second diameter is from 10 to 20.  
     
     
       12. A method for producing a single-walled carbon nanotube product comprising: 
       providing an anode at least a portion of which includes graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen;  
       providing a cathode in the atmosphere; and  
       inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product, wherein the growth promoter is selected from the group consisting of sulfur and a solid sulfide;  
       wherein, in the step of inducing the electric arc, a direct current of 100 to 150 amps dc is applied to thereby create a plasma.  
     
     
       13. A method for producing a single-walled carbon nanotube product comprising: 
       providing an anode at least a portion of which includes graphite powder, catalyst metal, and a growth promoter in an atmosphere containing hydrogen;  
       providing a cathode in the atmosphere; and  
       inducing an electric arc across the anode and cathode to thereby consume the anode and produce the single-walled carbon nanotube product, wherein the growth promoter is selected from the group consisting of sulfur and a solid sulfide;  
       wherein the growth promoter is present in the portion of the anode in an amount of 0.5 to 1 atom percent.  
     
     
       14. The method according to  claim 1 , wherein the acid is a member selected from the group consisting of 20-65% HNO 3  and 10-37% HCl. 
     
     
       15. The method according to  claim 1 , wherein the product is soaked for 24 to 48 hours. 
     
     
       16. The method according to  claim 1 , wherein the heating temperature is in a range from 400° C. to 1200° C. 
     
     
       17. The method according to  claim 1 , wherein the heating lasts for 2 to 4 hours in vacuum. 
     
     
       18. The method according to  claim 1 , wherein the hydrogen storage material has a hydrogen adsorption capacity higher than 3% by weight.